Given the temperature outside I am guessing thermostat is sticking, first open, then closed. Switch to inline, run the cap one full turn loose. Long post on that here: https://landroverforums.com/forum/di...46/#post887409

 

I ordered a 180 degree inline one. I didn't consider the cap. I'll see about that too. 🤔

I did watch an Atlantic British video about headgasket replacement, pretty involved. Did one on a 3 series BMW years ago that wasn't quite as in depth.

 

Aaaah. Open system seems like a much better move after reading that. Just elevating the overflow hose and losening the cap makes it open?

 

Yes it does

 

Make sure that there is no coolant in the crankcase , because then it's Game Over

 

So, today I went out and bled her again. Air didn't seem to be a problem, but my heater still isn't producing heat. I did some research on that, and apparently you can find a clog by grabbing the hoses, and feeling if one is substantially hotter than the other. I checked that. Both were faintly warm, so I guess that's inconclusive.

I guess my next steps are replace the thermostat, then flush the heater core? I'm at a bit of a loss here. If I pull out the glove box can I squeek my hand up into there to feel the core? Then I'd know if that's getting hot water.

 

@TheLastOne The hoses are enough the Discovery is a constant flow system. Check that your dampers are working, but flushing the heater core will not hurt, you should be see how the flow is. You should be able to clamp the rubber hoses to stop most of the coolant loss.

 

@Richard Gallant yeah. I would like to flush it, it's just 5 Degrees F outside so I'll need to pull her in the garage tonight I guess. You mentioned dampers. You mean the blend doors or gates? Not sure what they're called on the Rover.

 

Suggest you get one of these.
Do you still have a thermostat element in it? If so, warm engine up to 120 or 140 or so, buzz the engine up to about 2000 rpm for 30 seconds, feel heater hoses. They should be very warm to the touch, you should not be able to hold your hand on them. Feel top radiator hose forward section, it shoudl be cold. You are doing this because with the thermostat still closed all the flow should go through the heater core. If not hot, heater core is plugged. Once engine is fully warmed up and thermostat opens top radiator hose should get warm. Because heater core is full bypass type in super cold weather with heater going full blast thermostat won't open very much at idle, you would need to be going highway speed to get it up to temperature.